Late Fall Plant Evaluations

I've been holding off on this post for a couple weeks, thinking I needed a better sampling of plants in the garden than what I already had. But I simply kept neglecting to take those photos, when I was home on the weekends and during the brief times when it wasn't pouring rain. But really, I have plenty for this post, and I can catch other things later. In fact, I have more than enough for this post. So, for my sanity and yours, I'll break them up into separate posts by sections. This time, I'll cover a few things in the driveway island, though there's more I could (and should) show if only I could have motivated myself to snap a few photos with my phone before this latest storm hit. Oh well, outdated photos, it is.

I had just finished replanting the driveway island the two weekends before the hard freeze, and the plantings included many small seedlings, rooted cuttings, and divisions made at planting time. The predicted freeze had me a little on edge to see how the new planting would handle the cold.

While my family and I vacationed at the beach, I realized the Cerinthe major 'Purpurascens' wouldn't like the freeze. Once things thawed out, they looked like this:

Still alive, but definitely damaged. However, they've recovered well enough and really don't look too bad now. Perhaps if we get another hard freeze during winter, I'll remember to give them a bit of protection. Perhaps not.

The winds have swept clean much of the dead foliage cluttering the dead stems of Origanum 'Kent Beauty', but leaving many of the hop-like flower bracts. After a relatively brief ugly phase, it's returned to something more attractive. I still want to combine it with something evergreen that will intermingle with it and make less of a bare patch in winter. I've planted a form of Sedum spathulifolium at the base of one patch. We'll see how that plays out. I'm also considering the semi-evergreen Euphorbia cyparissias 'Fen's Ruby' (a la Flutter & Hum), but am leery of spreading euphorbias, even ones as airy as Fen's Ruby. I have noticed small creeping stems forming on the oregano already, which I usually don't expect to see until late winter spring. These are still not enough to fill in the dead space left by the sprawling flower stems, though.

I planted a lot of seedling Euphorbia rigida, after seeing them in several gardens this summer. It reseeds plentifully in some gardens, while others see nary a seedling at all. I have a feeling it's more likely to reseed in exposed, disturbed soil. By the time these seedlings are big enough to flower, I'm hoping the sedges and other plants around them will have filled in and there won't be so many seedlings that this euphorbia becomes a nuisance. I love the form and the glaucous foliage. Some of the seedlings were damaged by the cold and may die, but the majority of them, like the one below, are untouched.

Earlier in summer, I purchased a gallon container with three Erysimum (see the blooms here) from which I collected and sowed the seed. The resulting seedlings handled the cold without a care. There is a bit of damage from slugs and cutworms, which I've been fighting throughout the garden this fall.

I love Aster x frikartii 'Monch', but it has a tendency to flop in my garden, since I'm too lazy to cut it back in summer to create a shorter, sturdier plant. To fight the flop, I created three similar groupings, with the asters at the center of each. The surrounding plants are Calluna vulgaris, Molinia caerulea 'Variegata', and Stipa gigantea. The surrounding plants are sturdier and more upright than the asters, and either have evergreen foliage or dead stems that remain upright for most of the winter, supporting the asters during and after bloom and reducing the empty space that the aster and Molinia leave when their stems are cut in late winter.

I took a lot of small stem divisions of Veronica liwanensis to spread this flat, evergreen ground cover through the bed. Planted earlier this spring, the main patches have grown well but bloomed sparsely. I'm hoping they'll be covered in blue blooms in the coming spring.

Ironically, the bits of rooted stem I hastily planted look better than the main patches, where the old foliage apparently suffered a bit from the frost. This happens in the PNW with many super-cold hardy alpine or rock garden plants, which would normally be covered by snow when hard frosts arrive. Warm, wet weather like we've had this fall results in growth and reduced hardiness. However, it doesn't happen every year and these tough plants recover quickly in spring. The same thing has happened to Hutchinsia alpina and Alchemilla ellenbeckii, but both have filled back in and grown to several times their previous sizes the following years.

Possibly the biggest sources of anxiety in the freeze were the small Parahebe perfoliata I had grown from cuttings this summer. The one in the photo below looks a little frost-darkened, but none of the plants show any signs of permanent damage and have returned to their normal appearance. I'm more worried about keeping the slugs and cutworms away from the tender new shoots emerging from the base of each plant. Since the cuttings I took at work in cooler fall weather did better than the ones taken in the heat of summer, I'm also thinking of taking cuttings from my main plant this winter and keeping them in the greenhouse. I want this plant everywhere.


This Sedum spathulifolium is still holding its own against the lime thyme, but I still worry about how this accidental combination will work out once the thyme really starts growing. The thyme can pile up to almost 6 inches tall once it really starts growing, if not properly maintained. This particular clone of Sedum spathulifolium is a fairly compact, low-growing one out in the open, though it does seem to be growing larger and more upright in the thyme. Still, I've been trimming bits of thyme away from the sedum and pressing it down to keep the thyme from overtaking the sedum. I'm trying another, larger form of Sedum spathulifolium and the larger species Sedum oregonense in other areas and will eventually try combining them with the thyme, because I really like this combination and want to find a way to make it work with a little less maintenance.

I planted two Seseli gummiferum in this bed, and was curious to see how they'd handle the freeze. The yellowish leaves in the photo below eventually dropped cleanly, leaving the smaller tuft of leaves in the center. I think this one is a winner both for dying gracefully and winter interest, especially after seeing the mature versions at the St. Johns Pub in Portland.

I planted four Astelia 'Red Devil' this year, one a freebie in rough shape in another bed, and three purchased for the driveway island. All handled the cold without damage, even the ones in shady frost pockets. I had worried about that a bit. I planted them on the north sides of larger, taller plants to give them cooler conditions during the heat of summer, which these and many other New Zealand and Tasmanian plants appreciate, but in winter these locations become frost pockets. The temperature dropped to 18F in my garden during that freeze. But that really isn't very cold, even for here. I love the bold texture and metallic red foliage of this astelia, and plan to add more to the garden.

The cold intensified the color of the orange heathers. I have two or three different cultivars, with minor differences in color and growth habit, but I can't remember which is which.

The Euphorbia 'Nothowlee' (aka Blackbird) remained evergreen through the freeze. Something interesting and unexpected happened with the inflorescences, though. Before the freeze, they were mostly upright. After the freeze, the stems bent down in graceful umbrella shapes.

Of course, Salvia officinalis 'Berggarten' did just fine through the freeze. I'm looking forward to these small plants filling in.

I'm excited to watch this bed fill in. The plants are a bizarre mix of classic PNW (with the red laceleaf maple, heaths, and heathers) natives, Mediterranean herbs, cottage garden plants like the asters, and New Zealand flora. It sounds strange in print, but it already looks promising in real life.

Comments

  1. When I planted Cerinthe, I was sure it had soon died. The next spring there was a carpet of little seedlings. How that happened, I have no idea. Your thoughtful plant choices and placement are an inspiration

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    1. Aw, thanks, Ricki! I know my Cerinthe flowered and set seed the spring before last. I was just surprised that these seedlings didn't show up until two falls later.

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  2. I love reports like this, thank you for thanking the time to file this one. The Cerinthe major 'Purpurascens seedlings in my garden didn't miss a beat, it will be lovely next spring if they all make it. Euphorbia rigida seedlings are such odd things, it took home forever to get them to take hold and even now they aren't crazy, just perfect.

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    1. There will be lots more of these reports, so enjoy! My parents' house got a little colder than Portland in that freeze, as usual. It never seems like much, but it can make a big difference.

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  3. I'm a fan of Cerinthe. Even though they reseed freely, a prolonged freeze will wipe them out. But as long as one or two seeds germinate in Spring, I'm good. I also love Berggarten sage. The one was so successful that I planted cuttings in two new spots. I followed your lead with euphorbia blackbird; it will be it's first winter in the garden and so far it's looking great: thanks for the recommendation! The thyme/sedum combo is very appealing: doesn't your thyme suffer at all from the cold weather? It looks so fresh and gorgeous.

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    1. I wish I had gotten more Cerinthe seedlings. They didn't sprout well in the mulch that covers the bed I planted the originals in. I should wait to see how the Blackbirds I already have do over the next year or two before I get more, but I already want more of them. My thyme usually only suffers when we get one of those Arctic blasts, especially if it hasn't been maintained for a few years. I try to trim it back hard every year or two, which keeps it tight and prevents those dead patches that thyme can get, but while I was away from home it was allowed to grow uncontrolled and suffered major die-out even in the super mild winter we had last year.

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    2. In fact, most of it looked dead this spring, and I was going to tear it all out because it looked so awful. I did remove a lot of it, but I lost steam on that and it ended up coming back strongly. At least now most of it is nice and low. It hasn't started piling up and smothering itself.

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